1. Field of the Invention
The invention relates to an electrical conductor and particularly a conductor bar, or a partial conductor of a conductor bar, which can in particular be used in a generator or transformer, and into which conductor bar, or the partial conductor of a conductor bar, an optical measuring device can be integrated. Furthermore the invention relates to an optical measuring unit including an electrical conductor and an optical measuring device arranged in the conductor, and also to a method of producing such an electrical conductor.
2. Brief Description of the Related Art
In electrical generators, transformers, and also other electrical machines, conductors, so-called conductor bars (bars for short) are used for conducting the electrical current, in individual arrangement or as bar packets. These conductors are heated up rather considerably due to the current flux. If the temperature exceeds a certain maximum value, damage to the electrical conductor itself or also to other components adjacent to the conductor can occur. As far as desirable, a constant monitoring of the temperature is to be performed. In a few electrical machines known from the prior art, in particular in those which represent a large investment cost, and which are thus designed for a long lifetime, such temperature monitoring is already realized. For this purpose, a suitable sensor is placed at a place to be measured. The sensor then generates a measurement signal which is to be supplied for further processing via a signal lead from the sensor. In electrical machines, due to the often very high current fluxes and the strong electromagnetic fields built up as a consequence of these high current fluxes, conduction of an electrical signal is not reasonably possible. Moreover metallic sensors cannot be used at mass locations which lie at a high electrical potential. In order to prevent signal errors due to signal scattering, sensors which produce optical signals are therefore mostly used at the present time in electrical machines, the signals then being supplied for further processing via optical signal conductors, in particular optical waveguides. Moreover the electrical generators and transformers are at present embodied in a very compact construction, so that in particular the arrangement of the signal conductor raises constructional problems.
From German Offenlegungschrift DE 101 39 760 A1 there is for example known for this purpose a coil arrangement in which an optical waveguide used as a signal conductor is wound in with a winding body. The optical waveguide is in fact integrated into the winding body such that the external measurements of the winding body are thereby unchanged. However the production of the winding with the wound-in optical waveguide is an expensive manufacturing technology. In particular, a defective optical waveguide cannot easily be removed again and replaced with a new optical waveguide, without having to completely unwind the winding body.
There is also known from German Patentschrift DE 199 62 668 C1 an arrangement of an optical measuring device on a conductor. The conductor can for example be a stator or rotor winding of a generator. The conductor is pressed for this purpose into a groove of a bundle of stator laminations or rotor laminations, the groove being bounded by two groove sidewalls. The measuring device, which includes an optical sensor and an optical waveguide, is arranged on the long side of the groove remote from one of the two groove sidewalls. Thus if a sensor is arranged on a conductor according to this teaching, the constructional volume of the whole arrangement is increased at least corresponding to the dimensions of the optical waveguide and of the sensor. Furthermore, a quantity to be measured, for example temperature, can be determined only on the long side, i.e., above or below the conductor.
In all the known arrangements of the prior art, the sensors are respectively positioned on the outside of the electrical conductor. Thus hereby also only the temperatures abutting on the outsides are measurable.